A review of multi-functional SMA hybrid composites and past and present applications is presented. Shape memory alloy (SMA) materials such as nitinol have unique properties associated with the shape recovery effect and the material's phase changes that have proven useful in a variety of actuator and sensor applications. Because of their actuation and sensing abilities, SMA elements have been embedded in polymer matrix composites to aid in controlling the material's structural properties. The SMA hybrid composite materials have demonstrated varying success in applications such as vibration and shape control, creep resistance in structures, strain sensing and active damage control. In dynamic applications which require heating and cooling of the wires to start and stop the recovery process, the heating and cooling rates become limiting factors. Static applications for SMA hybrid composites have used the large recovery stress and/or strains of the embedded prestrained SMA wires and the inherent resistivity change. Restrictions on the use and extent of the SMA wire's recovery stress was an outcome of much of the early research. In present research, the leveraging of the SMA materials' unique properties by placement in specific composite structures or in specific applications has been attempted. Present applications that will be presented include: the adaptive compound cylinder concept for controlling radial dilation in composite cylinders, deflection control of composite structures, and improving composite materials' impact resistance by hybridizing with SMA elements.
展开▼
